Cross Layer Design for Efficient Video Streaming over LTE Using Scalable Video Coding

Rakesh Radhakrishnan, Balaaji Tirouvengadam, Amiya Nayak
2012 Network Protocols and Algorithms  
Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) offers high data rate capabilities to mobile users, and network operators are trying to deliver a true mobile broadband experience over LTE networks. Mobile TV and Video on Demand (VoD) are expected to be the main revenue generators in the near future, and efficient video streaming over wireless is the key to achieve this goal. Video services use both unicast and multicast video transmission based on its applications.
more » ... Multimedia Broadcast/Multicast Service (EMBMS) is defined in 3GPP specification to support download delivery and streaming delivery to group users in LTE mobile networks. In 3GPP Release 8 specification, the EMBMS transmission is classified into single-cell transmission and MBSFN (Multicast Broadcast Single Frequency Network) transmission. In this paper, we propose a Scalable Video Coding (SVC) based video streaming scheme with dynamic adaptations and a scheduling scheme based on channel quality for unicast and multicast video transmissions. In our proposed unicast scheme, Channel Quality Indicator (CQI) feedbacks from User Equipment's (UE) are used for dynamic adaptations and scheduling. Cross layer signaling between Medium Access Control (MAC) and Real Time Transport (RTP) protocols is used to achieve the channel dependent adaptation for unicast in video server. Simulation results for unicast indicate improved video quality for more number of users with reduced bit rate video traffic. Approximately 13% video quality gain is observed for users at the cell edge using this adaptation scheme. We have also proposed a scheduling scheme for multicast over MBSFN networks. This scheme optimizes the radio spectrum allocation by adaptive modulation and coding (AMC) and frequency scheduling based on distribution of users in different channel quality regions. Through simulations we demonstrate that spectrum savings in the order of 72 to 82% is achievable in different user distribution scenarios with our proposed scheme. Figure 3: LTE MBSFN system architecture [17] Authors of [18] present a packet scheduler for UMTS MBMS services. This packet scheduler is designed to deliver two different quality of service for users located in different locations of the same sector of a cell and power requirement of MBMS service is reduced with this. SE refers to the information rate that can be transmitted over a given bandwidth in a specific communication system. It constitutes a measure of how efficiently a limited frequency spectrum is utilized. This can be increased by using high modulation and coding index. Authors of [19] compare SE of MBSFN based LTE networks using different MCS selection algorithms. A typical unicast transmission will have 14 OFDM symbols per sub frame. The Cyclic Prefix (CP) used for MBSFN is longer than CP used in unicast, and this enables the UE to combine transmissions from different eNodeBs located far away from each other. Because of this, only 12 OFDM symbols per sub frame are used for MBSFN and only one sub frame per radio frame is allowed to use for one MBSFN bearer. Moreover, MBSFN reference signals are transmitted more frequently compared to cell-specific reference signals used for unicast transmission. These factors reduce the SE compared to unicast and total cell MBSFN SE calculations. Proposed Adaptation and Scheduling Schemes for Unicast and Multicast Video Transmissions An efficient scheme for channel quality based rate adaptation for unicast SVC video transmission is presented in Section 3.1. AMC and scheduling scheme for MBSFN video transmission is presented in Section 3.2. Unicast Adaptation and Scheduling Scheme Channel quality based adaptive bit rate selection scheme for video transmission over LTE network is proposed in this section. Adaptive bit rate is achieved using quality and temporal scalability features of SVC encoding. CQI reports from User Equipments (UEs) are used for the adaptation purpose, and this scheme is aimed at improving video quality of low and medium Network Protocols and Algorithms
doi:10.5296/npa.v4i4.2171 fatcat:qzmwhrul6rbq3h36xsxdk5yegq